Trouble down the line

Closure of a major Yorkshire rail link following collapse of a colliery spoil heap has been described as the rail industry’s worst landslide incident with services suspended for at least four months. Claire Symes and Paul Madill report.

First indication of the problems to come on the Doncaster to Goole rail line came on 9 February when a train driver reported a “rough ride” through the area close to Hatfield Colliery’s main spoil tip. This triggered monitoring of the line by Network Rail, but just three days later, the rail line was too distorted for services to continue and buses look set to replace trains on the section until at least this summer.

The “rough ride” was caused by a landslide in the spoil heap at the colliery, but Network Rail’s repairs to the rail line cannot start until the colliery completes its own remediation work. Northern Rail’s train services are currently being replaced with buses between Doncaster and Goole stations and closure of the rail line is estimated to be costing Network Rail in the region of £500,000 a week in fines.

The toe of the landslide has damaged a 400m section of the rail line

However, Network Rail says responsibility for the remediation lies with the colliery’s owner and the colliery is also expected to be liable for the costs of the closure.

“As far as we know, there have not been any major stability problems at Hatfield in the past,”

Mike O’Sullivan, Hargreaves

Hatfield is owned by ING Bank which was the main creditor of previous owner, Powerfuel, which went into receivership two years ago. The site is currently managed on a contract basis by Hargreaves, which operates a number of its own collieries in the north-east.

“The spoil heap next to the rail line is up to 30m high and has been built up over a number of years,” says Hargreaves communications manager Mike O’Sullivan. “As far as we know, there have not been any major stability problems at Hatfield in the past, although minor ground movements are common in most spoil heaps. However, some other spoil heaps on the other side of the Hatfield site are up to 40m high and show no sign of stability problems.”

Nonetheless, a Hargreaves company newsletter published shortly after it started work on the site in 2011 reveals that some stability work was undertaken on the spoil heaps at this time. O’Sullivan declined to comment on what this work involved or where on the site the work was carried out.

GE has also learnt that Arup is working with the colliery contractor to find a solution for the site but the consultant declined to comment on the project.

In a statement issued in early March, Hargreaves confirmed that the landslide has now stabilised and work on removing the 1.5M.t of debris is expected to start soon.

Network Rail says it will start to reinstate the damaged 400m section of line once the colliery has restored the area to the sub-formation. However, because no timescale has been put on reaching this point by the colliery, Network Rail says it can only estimate when the line will reopen. “Our best estimate is 16 to 18 weeks,” said one engineer on the scheme. For similar reasons, a Network Rail spokesperson could only put the price of the track recovery at “tens of millions of pounds”.

Failure mechanism

Although Hargreaves and Arup declined to comment on the mechanism of failure, images of the landslip have been analysed by Durham University Wilson professor of landslides Dave Petley, who believes heavy rain and the local geology may have played a part in the collapse. “It is an interesting landslide with both rotational and translational elements,” he said. “The local geology maps show that the tip has been constructed over a layer of alluvium and I believe that the failure started in this layer.

“This led to the ground under the railway moving forward and the heap shifted downwards. The toe of the landslide is now acting as a counterweight to the main slope.”

Petley suggested that any earthworks will need to start from the top of the slip. “It will be a challenging remediation,” he added. Petley says, historic maps show a culvert running under the tip so he believes ground conditions underneath may vary so the current stability issues may not be a widespread problem. “It is difficult to speculate on this though,” he added. “Nonetheless, it would be surprising if the heavy rainfall levels we have seen over the last year were not a factor.”

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